In an apparatus that measures and inspects a pattern that is formed on a semiconductor wafer, matching to a field of view of an inspection apparatus in a predetermined measurement position is performed using template matching technology. The template matching is a process that picks out a region, which coincides most with a template image that is registered in advance, from an image of a retrieval subject. For example, in PTL 1, an example of such a template matching method is described.
Measurement of a pattern on a semiconductor wafer using a scanning electron microscope is an example of an inspection apparatus that uses template matching. In the present apparatus, the field of view of the apparatus moves to an approximate position of a measurement position due to stage movement, but in terms of the positioning accuracy of the stage only, there are often cases in which large shifts occur in an image that is captured using a high magnification of the electron microscope. In addition, a wafer is not necessarily placed on the stage in the same direction each time, and a coordinate system (for example, an alignment direction of a chip of the wafer, or the like) of a wafer that is placed on the stage does not completely coincide with a driving direction of the stage, and this can also correspond to a cause of shifting in an image that is captured using a high magnification of the electron microscope. Template matching is performed in order to perform measurement and inspection at an accurate position by correcting such shift. Specifically, after performing alignment with an optical camera having a lower magnification than that of the electron microscope image, alignment is performed in multiple stages by performing alignment using the electron microscope image. Hereinafter, a case of performing alignment of a coordinate system of a water, which is placed on the stage, using an optical camera, will be described. In this instance, a case of performing alignment using an image of a plurality of chips, which are in positions that are separated from one another on a wafer (for example, chips on both the left and right ends of the wafer), will be considered. Firstly, an image of a unique identical pattern, which is within or in the vicinity of the respective chips (a pattern, which is relatively in the same position within the respective chips), is captured in a practical sense, and registered as a template. Normally, there are often cases in which a pattern, which is created on a wafer as an alignment pattern for an optical camera, is used as a unique identical pattern that is used in registration as a template. Next, an image is acquired in the respective chips by performing stage movement so that an image of a pattern that is registered as a template in the respective chips is captured. Template matching is performed on the acquired image. A shift amount of stage movement is calculated on the basis of respective matching positions that are obtained as a result, and matching of a coordinate system of stage movement and a coordinate system of the wafer, is performed with the shift amount set as a correction value of stage movement. In the alignment using the electron microscope that is performed subsequently, a unique pattern that is close to the predetermined measurement position is set as a template and registered in advance, and the relative coordinates of the measurement position viewed from the template are stored. Additionally, the relative coordinates in this case are decided by also taking correction amounts determined beforehand by the optical camera into consideration. Further, during determination of a measurement position from an image that is captured by the electron microscope, a matching position is decided by performing template matching in a captured image, and a point at which movement from the matching position of an amount that is equivalent to the relative coordinates stored in advance corresponds to a measurement position. Movement of the field of view of the apparatus up to a predetermined measurement position is performed using this kind of template matching.
In addition, in PTL 2, a method in which a template for template matching is created on the basis of design data of a semiconductor device, is described. If it is possible to create a template on the basis of design data, there is an advantage in that the labor of purposely acquiring an image with the inspection apparatus for template creation is not necessary, and the like. The invention also relates to template matching using this design data.